MASSAWA, Eritrea — Eritrean police have jailed three prominent pastors and a popular Christian singer recently, escalating a two-year government crackdown against the country’s evangelical Christians. Haile Naizgi, chairman of the Full Gospel (Mullu Wongel) Church, and Kifle Gebremeskel, chairman of the Eritrean Evangelical Alliance, were arrested at 6 a.m. at their homes in Asmara May 23. Four days later,…